Supplemental inflatable restraint systems require a cover which opens to provide a path for deployment of an air bag into the passenger compartment as it is inflated.
Some of the prior art pads or covers for air bag devices are not soft and do not match or conform to the styling and aesthetic requirements of an associated interior trim product in which the supplemental inflatable restraint system is housed. Such covers are often formed from injection molded thermoplastic elastomers or thermoplastic olefins. While such materials are suitable for mid-mount locations such as on the front vertical surface of an instrument panel, they do not perform well if subjected to radiant heating, e.g., sunlight directed through a front windshield of a vehicle.
Other prior art pads or covers include a foamed interior which provide a soft feel and an outer skin of cast plastisol, e.g., polyvinyl chloride (PVC) or urethane skin, ABS/PVC/nitrile tripolymer vacuum formable sheet, dry cast polymer skins, or injection molded PVC, which can be aesthetically matched to the material of the outer surface of an interior product which houses the supplemental inflatable restraint system.
Examples of such prior art pads or covers are shown in U.S. Pat. No. 3,708,179 which discloses mid-mounted doors formed of a layer of urethane foam and an outer cover of a plastisol skin material. The '179 structure is supported on a pair of spaced hinge pins for movement outwardly of the front vertical face of an instrument panel so as to permit deployment of an air bag into the passenger compartment at the passenger side of the front seat.
U.S. Pat. Nos. 4,946,653 and 4,893,833 disclose door configurations for closing an upper mount configured supplemental inflatable restraint system wherein the door is located in an upper surface of an instrument panel and moved upwardly toward the windshield of the vehicle when the air bag is deployed.
One problem with such prior art systems has been how to hold down the rear edge (from the in car position) of the door adjacent the rear edge of the deployment opening in the interior trim product. In the case of top doors, the rear edge is located at a point where children can pry the door open unless it is firmly fastened in place by interlocking mechanical members. One problem with such interlocking structure is that it may not allow for a prompt and repeatable release of the door when an air bag is inflated to impact against the underside of the door. In such cases, the access door may not fully open and thereby may hinder unobstructed deployment of the air bag into the passenger compartment of a vehicle. One solution to such problems is set-forth in U. S. Pat. No. 5,161,819 that provides two hook and loop fastener strips one strip located on each of first and second substrates to define a specified hold down force. The hold down force is maintained over periods of use and variations in temperature extremes so as to assure release of the door to provide unobstructed deployment of the air bag into a passenger compartment when vehicle impact causes a gas generator to inflate the air bag. Each of the fastener strips is connected to one of the substrates to form a tamper proof connection for holding the door in place in the deployment opening prior to supplemental inflatable restrain deployment. The fastener strips are arranged to either release in tension or shear to allow for unrestrained movement of the door into an upwardly pivoted position between a windshield and the passenger compartment of a vehicle when a vehicle impact causes the air bag to be inflated for deployment into the passenger compartment. While suitable for their intended purpose such a tamper proof hold down arrangements have a hold down force that is dependent upon the area of connection between the hook and loop components. Additionally, the hold down force will be dependent upon the alignment of the respective components one to the other. In some arrangements such considerations present problems of selection and assembly.
Another hold down mechanism for a door closure in an supplemental inflatable restraint deployment system is set forth in U.S. Pat. No. 5,066,037 wherein a flange on the door closure is fit within a U-shaped clamp. In such arrangements the locking flange and clamp must be separately positioned and aligned during the assembly of the supplemental inflatable restraint deployment system.